The present invention relates generally to the field of controlling a hydro-electric unit, and more specifically it relates to a method of switching a hydro-electric unit from group power control duty into the individual power control duty.
A method of switching a hydro-electric unit from a group power control duty into the individual power control duty, according to which the control system with an electro-hydraulic controller adapted to control, the hydro-electric unit is fed not with the output overall voltage available from the power setter for all the hydro-electric units under group control but with the output voltage available from the individual power setter.
The output voltage from the individual power pre-setter is also utilized to shape the signal required for changing the setting of the individual pre-setter to reduce the push when the hydro-electric unit is switched to the individual power control duty.
The afore-mentioned signal is shaped by comparing the output voltage from the individual power pre-setter with the output voltage from the servomotor position transducer of the inlet vanes of the hydro-electric unit.
The principal disadvantage of the heretofore-known method lies in the fact that switching of a hydro-electric unit into the individual power control duty is effected with no push, i.e., with no power variation, in the only case when the supply mains frequency does not differ from that of normal.
In all other cases switching of a hydro-electric unit into the individual control duty is accompanied with power push. The term powerpush means that the transition from one operational mode to another is accompanied by an abrupt change in the power.